﻿Shader "ProjectDanmaku/Eff_Explode"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        
        _Pos ("Position", Vector) = (0, 0, 0, 0) 
        _Radius ("Radius", Range(-0.5, 1)) = 0
        _Pow ("Power", float) = 5
    }
    SubShader
    {
        Tags
        {
            "RenderType"="Transparent"
        }
        LOD 100

        Pass
        {
            Blend SrcAlpha OneMinusSrcAlpha
            
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;

            float2 _Pos;
            float _Radius;
            float _Pow;

            v2f vert(appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                return o;
            }

            fixed4 frag(v2f i) : SV_Target
            {
                float strength = 1 - clamp(abs(distance(i.uv, _Pos) - _Radius), 0, 1);

                strength = pow(strength, _Pow);
                
                return fixed4(strength.xxxx * 0.5);
            }
            ENDCG
        }
    }
}